Put chickpeas in a large bowl and cover with cold water at least twice their volume. Leave to soak overnight.

The next day, drain chickpeas. In a medium saucepan, combine drained chickpeas and baking soda over high heat. Cook for about 3 minutes, stirring constantly. Add 6 1/2 cups water and bring to a boil. Cook at a simmer, skimming off any foam and any skins that float to the surface, from 20 and 40 minutes, depending on the type and freshness. Once done, they should be very tender, breaking easily when pressed between your thumb and finger, almost but not quite mushy.

Drain chickpeas. You should have roughly 3 cups (600 grams) now. Place chickpeas in a food processor and process until you get a stiff paste. Then, with the machine still running, add tahini paste, lemon juice, garlic and 1 1/2 teaspoons salt. Slowly drizzle in ice water and allow it to mix for about 5 minutes, until you get a very smooth and creamy paste.

Transfer hummus to a bowl, cover surface with plastic wrap, and let it rest for at least 30 minutes. If not using immediately, refrigerate until needed, up to two days. Remove from fridge at least 30 minutes before serving.